Dyrosaurus
Dyrosaurus was an extinct genus of marine dyrosaurid crocodyliform from the Eocene of North Africa. It was a large animal, reaching 6 meters in size. The type species D. phosphaticus possessed slender jaws with numerous recurved teeth, indicative of a primarily fish diet (similar to the extant gharial). Dyrosaurus teeth have smooth enamel and are long and often sharp, helping it to hunt fast-moving prey. French paleontologist Auguste Pomel named the genus in 1894 for Djebel Dyr, a mountain near Tebessa in Algeria, where its fossil vertebrae were found in a phosphate mine. Other remains had been found earlier in another phosphate mine in Tunisia and described as Crocodylus phosphaticus Thomas, 1893, which became the type species. Geological/Environmental Information Dyrosaurids are found in transitional marine sediments from the Late Cretaceous to Lower Eocene.10 This family is known mainly from Maastrichthian deposits in New Jersey and the late Cretaceous to early Paleogene rock from the Tethys Sea in northern and western Africa.11 Fossils have also been found from the Paleocene and Eocene strata of Pakistan, as well as South America, Brazil, India, Southern Asia as well as coastal. Generally dyrosaurids are recovered from coastal and estuarine deposits through North Africa and the Middle East confirming their existence as semi-aquatic animals.12 A newer specimen was found in the deposits of the Maria Farinha Formation, the Poty Quarry appears to be an important area because it contains the most complete exposed marine section of the Cretaceous-Paleogene transition in South America.13 Dyrosauridae had its greatest taxonomic diversity during the Early Paleogene but it appears as though the clade was able to obtain a greater and more widespread geographic distribution during the Late Cretaceous. The earliest records of dyrosaurids are either in or close to Africa with fragmentary occurrences from the Cenomanian of Sudan and Portugal and several other pre-Maastrichtian, Late Cretaceous discoveries in Egypt. Later, by the Maastrichtian of North America, the record of dyrosaurids became more complete by establishing a widespread distribution that appears to be maintained through the Paleocene and Eocene. (5)14 Many similarly sized adults but very few juvenile dyrosaurids have been found in the Oulad Abdoun Basin and Lower Eocene beds. This is indicative of juvenile Dyrosaurids living in freshwater environments whereas large adults live in marine environments. Marine environments are known to have been highly affected by the K-T mass extinction whereas freshwater environments were less affected. Therefore, under the assumption the juveniles lived in freshwater environments and adults lived in marine environments juveniles were able to survive better and the genus could avoid total extinction. Historical Information/Discovery French paleontologist Auguste Pomel named the genus Dyrosaurus in 1894 for Djebel Dyr, a mountain near Tebessa in Algeria where its fossilized vertebrae were found in a phosphate mine.16 17 Thévenin (1911a, 1911b), with some better preserved material, was the first to confirm indisputably that Dyrosaurus phosphaticus was a Lower Eocene crocodyliform. Many dyrosaurid remains are known, but unfortunately they are often poorly preserved which makes it difficult for paleontologists to get a strong understanding of the family. 18 The genus Dyrosaurus was created by A. Pomel (1894a) after M. Philippe Thomas discovered teeth and bone fragments from the Lower Eocene of Tunisia as Crocodilus Phosphaticus.19 In 1903, the family Dyrosauridae was named by Giuseppe de Stefano referring to the locality for the holotype was found in Djebel Dyr, Algeria.20 Stephanie Jouve found and published her results on the study of Dyrosaurus maghiribensis a species of the genus Dyrosaurus in 2005. Description and Paleobiology Category:Paleogene crocodylomorpha Category:Extinct animals of Africa Category:Archosaur stubs Category:Marine crocodiles